I would replace the hops myself. If the grains are not crushed I would give a couple a chew and if they taste at all stale I would replace those as well. Unless they're pre-crushed in which case I would just replace them. The DME and extract can will be fine unless they're past any expiration date they may have. The dry yeast should be fine as well.
Ultimately you don't want to waste weeks of time brewing a sub-par beer for the sake of a few dollars. In my opinion anyway - it's your beer ultimately.